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$Id: dwarf_get_ranges.3 3644 2018-10-15 19:55:01Z jkoshy $
.Dd November 9, 2011 .Dt DWARF_GET_RANGES 3 .Os .Sh NAME .Nm dwarf_get_ranges .Nd retrieve non-contiguous address ranges .Sh LIBRARY .Lb libdwarf .Sh SYNOPSIS n libdwarf.h .Ft int .Fo dwarf_get_ranges .Fa "Dwarf_Debug dbg" .Fa "Dwarf_Off offset" .Fa "Dwarf_Ranges **ranges" .Fa "Dwarf_Signed *cnt" .Fa "Dwarf_Unsigned *byte_cnt" .Fa "Dwarf_Error *err" .Fc .Ft int .Fo dwarf_get_ranges_a .Fa "Dwarf_Debug dbg" .Fa "Dwarf_Off offset" .Fa "Dwarf_Die die" .Fa "Dwarf_Ranges **ranges" .Fa "Dwarf_Signed *cnt" .Fa "Dwarf_Unsigned *byte_cnt" .Fa "Dwarf_Error *err" .Fc .Sh DESCRIPTION Function .Fn dwarf_get_ranges retrieves information about the non-contiguous address ranges associated with a DWARF debugging information entry. Information about address ranges is returned as an array of descriptors of type .Vt Dwarf_Ranges , with each .Vt Dwarf_Ranges descriptor describing one address range entry.
p Argument .Ar dbg should reference a DWARF debug context allocated using .Xr dwarf_init 3 .
p Argument .Ar offset is an offset, relative to the .Dq ".debug_ranges" section, to the start of the desired list of address ranges. The offset of an address ranges list is indicated by the .Dv DW_AT_ranges attribute of a debugging information entry.
p Argument .Ar die (function .Fn dwarf_get_ranges_a only) is ignored in this implementation; see the section .Sx "Compatibility Notes" below.
p Argument .Ar ranges should point to a location that will be set to a pointer to an array of .Vt Dwarf_Ranges descriptors.
p Argument .Ar cnt should point to a location that will be set to the number of entries returned. If argument .Ar byte_cnt is not NULL, it will be set to the number of bytes occupied by the returned entries in the .Dq ".debug_ranges" section.
p If argument .Ar err is not NULL, it will be used to store error information in case of an error.
p .Vt Dwarf_Ranges descriptors are defined in the header file n libdwarf.h , and consists of the following fields: l -tag -width ".Va dwr_addr1" t Va dwr_addr1 The first address offset, whose meaning depends on the type of the entry. t Va dwr_addr2 The second address offset, whose meaning depends on the type of the entry. t Va dwr_type The type of this address range entry: l -tag -width ".Dv DW_RANGES_ENTRY" -compact t Dv DW_RANGES_ENTRY A range list entry. For this type of entry, the fields .Va dwr_addr1 and .Va dwr_addr2 hold the beginning and ending offsets of the address range, respectively. t Dv DW_RANGES_ADDRESS_SELECTION A base address selection entry. For this type of entry, the field .Va dwr_addr1 is the value of the largest representable address offset, and .Va dwr_addr2 is a base address for the beginning and ending address offsets of subsequent address range entries in the list. t Dv DW_RANGES_END An end of list mark. Both .Va dwr_addr1 and .Va dwr_addr2 are set to 0. .El .El .Ss Memory Management The memory area used for the array of .Vt Dwarf_Ranges descriptors returned in argument .Ar ranges is owned by the .Lb libdwarf . The application should not attempt to directly free this pointer. Portable code should instead use .Fn dwarf_ranges_dealloc to indicate that the memory may be freed. .Sh RETURN VALUES These functions return .Dv DW_DLV_OK when they succeed. They return .Dv DW_DLV_NO_ENTRY if there is no address range list at the specified offset .Ar offset . In case of an error, they return .Dv DW_DLV_ERROR and set the argument .Ar err . .Sh EXAMPLES To retrieve the address range list associated with a debugging information entry, use: d -literal -offset indent Dwarf_Debug dbg; Dwarf_Die die; Dwarf_Error de; Dwarf_Addr base; Dwarf_Attribute *attr_list; Dwarf_Ranges *ranges; Dwarf_Signed cnt; Dwarf_Unsigned off, attr_count, bytecnt; int i, j; if ((ret = dwarf_attrlist(die, &attr_list, &attr_count, &de)) != DW_DLV_OK) errx(EXIT_FAILURE, "dwarf_attrlist failed: %s", dwarf_errmsg(de)); for (i = 0; (Dwarf_Unsigned) i < attr_count; i++) { if (dwarf_whatattr(attr_list[i], &attr, &de) != DW_DLV_OK) { warnx("dwarf_whatattr failed: %s", dwarf_errmsg(de)); continue; } if (attr != DW_AT_ranges) continue; if (dwarf_formudata(attr_list[i], &off, &de) != DW_DLV_OK) { warnx("dwarf_formudata failed: %s", dwarf_errmsg(de)); continue; } if (dwarf_get_ranges(dbg, (Dwarf_Off) off, &ranges, &cnt, &bytecnt, &de) != DW_DLV_OK) continue; for (j = 0; j < cnt; j++) { if (ranges[j].dwr_type == DW_RANGES_END) break; else if (ranges[j].dwr_type == DW_RANGES_ADDRESS_SELECTION) base = ranges[j].dwr_addr2; else { /* * DW_RANGES_ENTRY entry. * .. Use dwr_addr1 and dwr_addr2 .. */ } } } .Ed .Sh COMPATIBILITY Function .Fn dwarf_get_ranges_a is identical to .Fn dwarf_get_ranges , except that it requires one additional argument .Ar die denoting the debugging information entry associated with the address range list. In this implementation of the .Lb libdwarf , the argument .Ar die is ignored, and function .Fn dwarf_get_ranges_a is only provided for compatibility with other implementations of the DWARF(3) API. .Sh ERRORS These function can fail with: l -tag -width ".Bq Er DW_DLE_NO_ENTRY" t Bq Er DW_DLE_ARGUMENT One of the arguments .Ar dbg , .Ar ranges or .Ar cnt was NULL. t Bq Er DW_DLE_NO_ENTRY There is no address range list at the specified offset .Ar offset . .El .Sh SEE ALSO .Xr dwarf 3 , .Xr dwarf_ranges_dealloc 3